Method and apparatus for generating electrical current

ABSTRACT

Method and system for generating electrical energy from a volume of water.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation Application of U.S patentapplication Ser. No. 14/073,840, entitle “METHOD AND SYSTEM FORGENERATING ELECTRICAL ENERGY FROM WATER”, filed Nov. 6 2013, co-pendingat the time of filing; which is a Continuation Application of the U.S.patent application Ser. No. 13/235,274, entitled “METHOD AND SYSTEM FORGENERATING ELECTRICAL ENERGY FROM WATER”, filed Sep. 16, 2011, copendingat the time of filing; which is a Continuation Application of the U.S.patent application Ser. No. 12/395,585, entitled “METHOD AND SYSTEM FORGENERATING ELECTRICAL ENERGY FROM WATER”, filed Jan. 26, 2009, copendingat the time of filing; which application claims priority benefit of U.S.Provisional Patent Application No. 61/023,313, filed Jan. 24, 2008; eachof which, to the extent not inconsistent with the disclosure herein, isincorporated by reference.

STATEMENT OF GOVERNMENT LICENSE RIGHTS

This invention was made with Government support under Contract No.AT-002362 and AR-44813 awarded by the National Institutes for Health andunder Contract No. N00014-05-1-0773 awarded by the Office of NavalResearch. The Government has certain rights in the invention.

BACKGROUND OF THE INVENTION

Satisfying the world's energy needs is a demanding endeavor. Presently,fossil fuels are responsible for supplying the bulk of these worldwideneeds. However, fossil fuel supplies are finite, their consumption oftenhas adverse environmental effects, their cost widely variable andsomewhat unpredictable, and independence from them is long considered tobe politically advantageous.

Alternative energy sources are being actively sought and developed.Solar and wind energy are attractive alternatives to fossil fuels. Windfarms have been developed and energy from them complements conventionalenergy supply. The promise of efficient and cost effective solar energyhas yet to be realized, although considered to be a future solution tothe worldwide energy problem.

Solar radiation, at its maximum produces about 1000 Watts/m². Solarcells can operate up to 30% efficiency, but typical values of efficiencyfor the most economical units are about 15-20%. Hence, typical output isabout 200 Watts/m², or about 20,000 μW/cm² at full solar radiation.Under more typical lighting conditions, the output would be an order ofmagnitude lower, about 2,000 μW/cm². Typical photovoltaic output valueis about 12,000 μW/cm² at full sun at the equator during the vernalequinox at midday, which is the absolute peak. More typical values, butstill under bright conditions, would be an order of magnitude lower,perhaps 1,200 μW/cm². The benchmark for commercial photovoltaic cells infairly bright light is from about 1,000 to about 2,000 μW/cm².

Despite the advances made in harnessing energy from the sun, a needexists to develop solar energy systems that provide electrical energy inan efficient and cost effective manner. The present invention seeks tofulfill this need and to provide further related advantages.

SUMMARY OF THE INVENTION

The present invention provides a method and system for generatingelectrical energy from a volume of water.

In one aspect, the invention provides a method for generating electricalenergy from a volume of water. In one embodiment, the method includescontacting a volume of water with a hydrophilic surface and applyingenergy to the volume of water to provide an exclusion zone in the volumeof water at the interface of the hydrophilic surface and the water, anda bulk zone in the volume of water outside of the exclusion zone;providing a first electrode in the exclusion zone and a second electrodein the bulk zone; and extracting electrical energy from the volume ofwater by connecting a load across the electrodes.

The applied energy can be radiant energy from the sun or infraredradiant energy from a local environment.

The method for providing electrical energy from a volume of waterincludes comprising connecting a load across first and second electrodesin contact with a volume of charge-separated water, wherein the volumeof water is in contact with a hydrophilic surface in liquidcommunication with the water defining an exclusion zone at an interfaceof the hydrophilic surface and the water, and a bulk zone in the volumeof water outside of the exclusion zone, wherein the first electrode isin the exclusion zone, and wherein the second electrode is in the bulkzone.

In another aspect of the invention, a system for generating electricalenergy from a volume of water is provided. The system includes ahydrophilic material having a hydrophilic surface; a vessel forreceiving the hydrophilic material and a volume of water; a firstelectrode positioned in the vessel proximate to the hydrophilic surface;and a second electrode positioned in the vessel distal to thehydrophilic surface.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a representative system forcarrying out a method of the invention;

FIGS. 2A and 2B are graphs comparing the exclusion zone expansion ratioas a function of wavelength of applied energy; 2A UV-Vis, 2B IR;

FIG. 3 is a graph illustrating voltage decrease over time in an opencircuit with no infrared irradiation;

FIG. 4 is a graph illustrating current over time in a closed circuitwith a 10K resistor;

FIG. 5 is a graph illustrating voltage over time in an open circuit withinfrared radiation;

FIG. 6 is a graph showing power generated as a function of pH;

FIG. 7A is an image of an exclusion zone prior to exposure to infraredradiation, the exclusion zone (EZ) is denoted by the absence ofmicrospheres;

FIG. 7B is an image of the exclusion zone after 5 min exposure to lightfrom LED31-PR; approximate size of incident beam is shown;

FIG. 8A is a graph comparing exclusion zone expansion ratios as afunction of exposure time for three infrared sources (LED17-PR,LED20-PR. and LED31-PR, lower power for LED31-PR);

FIG. 8B is a graph comparing exclusion zone expansion ratios as functionof time during 10 min exposure at different intensities (0.21 mW, 0.34mW, and 1.20 mW) using LED20-PR;

FIG. 9A is a graph comparing exclusion zone expansion ratios atdifferent depths during 3.5 min, 5 min, and 7 min exposures of 3.1 μmradiation;

FIG. 9B is a graph comparing exclusion zone expansion ratios with 5 minexposure to 3.1 11 m radiation focused at a series of distances from aNAFION® surface;

FIG. 10A is a graph comparing pH change over time following addition ofwater to a NAFION sheet; pH values were measured at 5 s intervals usinga miniature pH probe positioned at three distances from the NAFION sheet(1 mm, 5 mm, and 10 mm); a wave of protons is generated as the exclusionzone forms providing lower pH; at a distance of 1 mm, the pH droptransiently exceeds 3 pH units, which represents a hydrogen ion increasein excess of 1,000 times;

FIG. 10B is an image of a chamber containing a NAFION tube (bottom)filled with water containing pH-sensitive dye; view is normal to thewide face of a narrow chamber; image obtained 5 min after dye-containingsolution was added to the tube; the dark color indicates pH<3; thelighter colors above indicate progressively higher pH levels with nearneutrality at the top;

FIG. 11 is a graph comparing potential (mV) measured as a function ofdistance from the surface of representative hydrophilic materials(NAFION and poly(acrylic acid) gel) useful in the method of theinvention; substances are depicted as “inside” and water is “outside;”

FIG. 12 is a graph of voltage (V) over time using a platinum cathode andzinc electrode;

FIG. 13 is a graph corresponding to FIG. 12 showing current (amperes)over time;

FIG. 14 is a graph of voltage (V) over time using a platinum cathode andzinc electrode using glass slides that are twice (2×) larger than thoseused to obtain the record shown in FIG. 12; and

FIG. 15 is a graph corresponding to FIG. 14 showing current (amperes)over time.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method and system for generatingelectrical energy from a volume of water. In the method, electricalenergy is extracted from the volume of water that is subject to or hasbeen subject to applied energy, such a radiant energy from the sun orthe local environment.

In one aspect, the invention provides a method for generating electricalenergy from a volume of water. In one embodiment of the method, a volumeof water is contacted with a hydrophilic surface and subjected to theapplication of energy to provide an exclusion zone at the interface ofthe hydrophilic surface and the water. A bulk zone in the volume ofwater is formed outside of the exclusion zone. Charge separation isinduced in the volume of water by applying energy to the volume ofwater. Electrical energy is extracted from the volume of water byproviding a first electrode in the exclusion zone and a second electrodein the bulk zone, and connecting a load across the electrodes.

As used herein, the term “exclusion zone” refers to a region of thevolume of water created at the interface of the hydrophilic surface andthe water where solutes and particles are excluded. The term “bulk zone”refers to the region of the volume of water outside the exclusion zone.The exclusion zone results from the application of energy (e.g., radiantenergy) to the volume of water. The exclusion zone builds withincreasing applied energy.

Application of energy to the volume of water in contact with thehydrophilic surface results in the formation of the exclusion zone. Inthe process, charge separation is induced in the volume of water. Asused herein, the term “charge separation” refers to the physicalseparation of negative charges (e.g., solutes, particles, ions) frompositive charges (e.g., solutes, particles, ions) in the volume ofwater. In general, the exclusion zone is a region of negative charge andthe bulk zone is a region of positive charge (e.g., hydronium ions, freeprotons).

The size and shape of the exclusion zone formed in the method of theinvention varies greatly depending on the nature of the hydrophilicsurface, its size and shape, the nature of the volume of water, and theenergy applied. The size of the exclusion zone is variable and dependenton the applied energy: the greater the applied energy, the greater thesize of the exclusion zone. The exclusion zone can extend up to a meteror more from the hydrophilic surface. The exclusion zone can thereforeextend from the hydrophilic surface any distance from about 1 nm to ameter or more. In certain embodiments, the exclusion zone can extend adistance of from one to two millimeters from the hydrophilic surface. Inother embodiments, the exclusion zone can extend a distance of fromabout 200 μm to about 700 μm from the hydrophilic surface. The shape ofthe exclusion zone is also variable. For example, when the hydrophilicsurface is a sheet positioned against a wall of the vessel containingthe volume of water, the exclusion zone extends into the volume of wateraway from the surface of the hydrophilic surface. When a sheet ofmaterial having two hydrophilic surfaces is placed in a volume of water,the exclusion zone extends into the volume of water away from eachsurface. For a sphere of hydrophilic material having a hydrophilicsurface, the exclusion zone extends radially into the volume of wateraway from the sphere (e.g., shell). In other embodiments, the exclusionzone extends into the volume of water non-uniformly. For examples, theexclusion zone can have the form of a cone narrowing into the volume ofwater. Exclusion zones having a plurality of cones extending into thevolume of water have also been observed. Schematic illustration of thevolume of water having exclusion and bulk zones is shown in FIG. 1.

Exclusion zones were not observed with materials having hydrophobicsurfaces, such as silicon rubber, nylon, carbon, quartz, and a plasticparaffin film (PARAFILM®, is a registered trademark of Bemis Co. INC. OFNeenah, Wis.), hereinafter referred to as “PARAFILM”. In general, thematerials having surfaces that are highly charged (e.g., sulfonatedtetrafluoroethylene copolymer (NAFION 117 polymer), polyacrylic acidgels) exhibit the largest exclusion zones, while those that are leastcharged (e.g., polyvinyl alcohol gels) exhibit the smallest exclusionzones. (NAFION®, hereinafter referred to as “NAFION” is a registeredtrademark of E.I. Du Pont De Nemours and Company Corporation ofWilmington, Del.) In all cases, the region beyond the exclusion zone hadnet positive charge, confirmed by measurements of pH, which showed lowpH and therefore high hydrogen ion concentration. In some experimentsthe pH was as much as four units lower than the original water pH.However, the situation is reversed in the case of positively chargedsurfaces. These included positively functionalized polystyrene gelbeads, and SELEMION® positively functionalized ion exchange resin(SELEMION®, hereinafter referred to as “SELEMION” is a registeredtrademark of AGC Engineering Co., LTD. of Chiba, Japan). In such casesthe potential was 100-200 mV positive at the surface, declining to zeroat the edge of the exclusion zone. The bulk water beyond had high pHinstead of low pH. In these cases of positively charged surfaces, theexclusion zones were found to be smaller and somewhat more ephemeralthan those next to the negatively charged surfaces.

The volume of water required for the method of the invention is notcritical. The method is applicable to nanoscale volumes of water and toexpansive volumes of water (e.g., lakes and oceans). The pH of thevolume of water can vary (e.g., from about 2 to about 11). It has beenobserved that relatively more electrical energy can be obtained by themethod at low pH (e.g., pH>about 4). The volume of water can includesolutes such as salts. Suitable salts include potassium chloride andsodium chloride. Other salts, such as those used in chemical batteriescan also be used. The ionic strength of the volume of water can alsovary. Ionic strengths up to about 5M have provided reasonable output.Electrical energy has been extracted from volumes of water having ionicstrength up to about 5M, and optimal energy has been obtained at ionicstrengths from about 100 mM to about 2M.

In the method, the exclusion zone is formed adjacent to the hydrophilicsurface. As used herein, the term “hydrophilic surface” refers to asurface of a material having a contact angle less than 90 degrees forwater. The hydrophilic surfaces may be charged or uncharged. The chargedhydrophilic surfaces may be mixed charge surfaces. The chargedhydrophilic surfaces may have a net positive charge or a net negativecharge.

Suitable materials having hydrophilic surfaces include hydrophilic gels(e.g., polyacrylic acid gels, polyvinyl alcohol gels, polyacrylamidegels, polyHEMA gels, collagen gels, actin gels, and agarose gels),biological materials (e.g., muscle tissue, vascular endothelium, xylem,oxtail tendon, seaweed, and plant root), self-assembled monolayersincluding carboxyl group-containing monolayers and polyethyleneglycol-containing monolayers (e.g., supported on metal surfaces such asgold), polymeric surfaces (e.g., ionomer surfaces) including sulfonicacid-containing polymer surfaces (e.g., sulfonated tetrafluoroethylenecopolymer surface also known as NAFION), inorganic surfaces (e.g.,surfaces containing titanium dioxide, silicon, zinc, lead, tungsten,aluminum, tin, and mica), and ion exchange resins and materials.

As noted above, suitable materials having hydrophilic surfaces may havea variety of shapes. In one embodiment, the hydrophilic material is asheet having a rectangular hydrophilic surface. In another embodiment,the hydrophilic material is a particle (e.g., microsphere ornanosphere). In other embodiments, the hydrophilic material includes aplurality of hydrophilic beads (e.g., mixed charged beads, negativelycharged beads, positively charged beads).

In one embodiment, the hydrophilic material is ice. Exclusions zoneshave been observed for each of the hydrophilic materials noted above.

As noted above, in the method, a volume of water is contacted with ahydrophilic surface and subjected to the application of energy.Application of energy increases the size of the exclusion zone. In oneembodiment, applying energy includes irradiating the volume of waterwith electromagnetic radiation. Suitable electromagnetic radiationincludes radiation absorbed by the volume of water (e.g., wavelengths inthe range from about 200 nm to about 10,000 nm). In the method, infraredwavelengths are the most effective wavelengths. In one embodiment, theradiant energy has a wavelength of about 3 μm.

The applied energy can be radiant energy from the environment such assolar energy (e.g., ultraviolet, visible, near infrared, and infraredradiation) and heat from the local environment (infrared radiation).

Although radiant energy is the source of energy applied to the volume ofwater, in one embodiment of the method, the size of the exclusion zonecan be increased by applying a voltage across the electrodes.

In the method, electrical energy is extracted from the charge-separatedvolume of water by connecting a load across the first and secondelectrodes. The nature of the electrodes is not particularly critical.Suitable electrodes include platinum, zinc, aluminum, stainless steel,and copper electrodes. The first and second electrodes may the same ordifferent.

The load can be connected after a predetermined period of time afterinducing charge separation (i.e., after applying energy to the volume ofwater). Alternatively, the load can be connected during application ofenergy (e.g., applying radiant energy to the volume of water) in whichcase electrical energy is extracted from the volume of water at the sametime that energy is applied to the volume of water.

Thus, in one embodiment of the method, electrical energy is extractedfrom a volume of water by connecting a load across first and secondelectrodes in contact with a volume of charge-separated water, whereinthe volume of water comprises a hydrophilic surface in liquidcommunication with the water defining an exclusion zone at an interfaceof the hydrophilic surface and the water, and a bulk zone in the volumeof water outside of the exclusion zone, wherein the first electrode isin the exclusion zone, and wherein the second electrode is in the bulkzone. As noted above, “charge-separated water” refers to water incontact with a hydrophilic surface that initiates the formation of theexclusion zone having a net charge opposite that of the bulk zone.

In another aspect of the invention, a system for extracting electricalenergy from a volume of water is provided. In one embodiment, the systemincludes a hydrophilic material having a hydrophilic surface, a vesselfor receiving a hydrophilic surface and a volume of water; a firstelectrode positioned proximate to the hydrophilic surface; and a secondelectrode positioned distal to the hydrophilic surface. When the vesselhas received a volume of water and energy has been applied to the volumeof water, the first electrode is positioned in an exclusion zone formedat the interface of the hydrophilic surface and the water, and thesecond electrode is positioned in a bulk zone in the volume of wateroutside of the exclusion zone.

In one embodiment, the system includes only those components describedabove (i.e., the system consists of the noted components). In anotherembodiment, the system includes those components described above andother components that do not alter the characteristics of the system(i.e., the system consists essentially of the noted components).Components that are excluded from this embodiment include components andconditions used in methods for the electrolysis of water, methods foranalyzing water samples, and electrochemical analytical and syntheticmethods carried out in water.

FIG. 1 is a schematic illustration of a representative system forcarrying out the method of the invention. Referring to FIG. 1, system100 includes vessel 10 that contains volume of water 12 and hydrophilicmaterial 14 having hydrophilic surface 16. On application of energy(e.g., radiant energy), exclusion zone 20 and bulk zone 22 form involume of water 12. Electrode 32 is positioned in the exclusion zone andelectrode 34 is positioned in the bulk zone. Electrical energy isextracted from the volume of water by applying a load 40 acrosselectrodes 32 and 34. Absent continued application of applied energy,the exclusion zone contracts. Application of energy during theapplication of a load allows for maintenance of the exclusion zone(i.e., charge separation) and simultaneous extraction of electricalenergy. The following provides a further describes the method of theinvention. Unexpected phenomenon was observed in water next tohydrophilic surfaces. In a zone up to several hundred micrometers fromthe hydrophilic surface, solutes were excluded. Subsequent studiesshowed that the solute-excluding region was physico-chemically differentfrom ordinary water, and probably liquid crystalline. Qualitativedifferences between this vicinal water and the bulk water farther fromthe hydrophilic surface were demonstrated using NMR, infrared radiation,and UV-Vis optical absorption. An additional unexpected result was alsoobserved: the excluding region was negatively charged. The potentialdifference between the vicinal water and water remote was approximately200 mV, decreasing exponentially with distance from the surface, towardzero potential difference at the end of the exclusion zone.

The results indicate a loss of positive charge from otherwise neutralwater. This lost positive charge was determined to reside in the aqueouszone beyond the exclusion zone. Methods showed a large protonconcentration in this bulk region. In dynamic experiments with pHprobes, a wave of protons was detected flowing away from the vicinalwater and toward the more distant bulk water, as the exclusion zone wasgrowing. The result is charge separation in the water.

When an entity whose surface is hydrophilic is placed into water,ordering of water molecules next to the surface immediately begins. Theordered entity is negative. As this zone builds, the quantity ofnegative charge builds. Meanwhile, the complementary positive chargesbuild in the zone beyond this ordered zone to provide charge separation.The charge separation is sustained. In the method of the invention,electrical current is drawn and thereby useful work obtained fromcharge-separated water.

In the method of the invention, the buildup of water structure, andhence the separation of charge, is powered by incident radiant energy(i.e., photons). In an experiment, a chamber lined on one side with ahydrophilic surface (i.e., NAFION) was filled with an aqueous suspensionof polystyrene microspheres. Within several minutes the microspheresmoved away from the surface leaving an exclusion zone. This zonegenerally remained stable for hours. When light was added the exclusionzone immediately began growing, and within five minutes it had grownsubstantially. When the light source was extinguished, the exclusionzone returned to its initial size. The effect of incident light isreversible.

Growth of the exclusion zone was wavelength sensitive. FIGS. 2A and 2Bare graphs comparing exclusion zone expansion ratio (defined as theratio of the exclusion zone width after application of energy to thecontrol state, which is the width of the exclusion zone prior to theapplication of energy) as a function of wavelength (2A UV-Vis and 2BIR). Throughout the ultraviolet-visible range the intensity wasmaintained constant; and, the same throughout the infrared range (on theorder of 100 μW). In the latter series, intensities were lower than inthe former series. All wavelengths increased the size of the negativezone, and the increase was wavelength sensitive. The most powerfuleffect occurred at a wavelength of 3 μm. With mode intensity (271 μW) at3 μm, in five minutes the exclusion zone (EZ) increased by almost afactor of three.

It is noteworthy that 3 μm is the wavelength most strongly absorbed bywater, and it causes heating. The temperature increase was measured atvarious points in the chamber. During the five-minute exposure, in noinstance did the temperature increase exceed 1° C. demonstrating thatany effect of heating must have been secondary. The major impact ofthese photons appears to be non-thermal, although the exact mechanism(i.e., how the photonic energy brings about ordering of exclusion zonewater and charge separation) remains unclear.

The following experiments determined that electrical power can be drawnfrom the charge-separated water. The setup included a NAFION sheet,secured within a sandwich of plastic sheets each containing a large openwindow, so that the NAFION sheet was exposed to water. A stainlesssteel-mesh electrode was placed immediately adjacent to the exposedNAFION sheet on one side. This served as the negative electrode. Thepositive electrode, another stainless steel mesh, was placed somedistance from the sheet, either on the same, or the opposite side as thenegative electrode. The second electrode was positioned so as to liebeyond the exclusion zone. The entire assembly was immersed in water.The two electrodes were either left open circuited, for potentialdifference measurements, or connected by a load resistor, arbitrarilychosen at 10 Kohms, through which current could flow.

A potential difference on the order of 100-200 mV was typicallyrecorded. The voltage was high at first, but generally declined withtime, depending on whether the load resistor was or was not attached.Importantly, the voltage never fell to zero. A fraction of the initialvoltage persisted indefinitely, implying that energy was consistentlyflowing into the system to recharge the system (infrared energy wascontinuously available to power the system). FIG. 3 is a graphillustrating voltage decrease over time in an open circuit with noinfrared irradiation. FIG. 4 is a graph illustrating current over timein a closed circuit with a 10 K resistor.

Experiments were then undertaken to demonstrate that incident infraredillumination increases power output in the system. FIG. 5 is a graphillustrating voltage over time in an open circuit with infraredirradiation. This data was obtained after the voltage had alreadydiminished considerably from an initial value. Turning on the lightcaused an immediate (within several minutes) return to the initial (200mV) voltage, which was sustained even for some time after the light hadbeen turned off.

Lowering the pH of the volume of water tended to increase power asindicated in FIG. 6. Adding salt to the volume of water induces asubstantial positive effect on power production, probably because of theincreased conductivity of the solution. Potassium chloride and sodiumchloride exert similar effects. In the concentration range 0.1 M to 1 M,power output increased to 150 microwatts. Considering theelectrode-surface areas of appoximately 3 cm², this increase amounts toabout 50 μW/cm².

Examples of exclusion zones are illustrated in FIGS. 7A and 7B.Referring to FIGS. 7A and 7B, the exclusion zones are adjacentnucleating surfaces and are denoted by the absence of microspheres. Asnoted above, the exclusion zone is distinct from bulk water. A series ofmeasurements including UV-Vis absorption spectra, infrared and NMRimaging, and electrical polarization showed that water in the exclusionzone was less mobile and more ordered than bulk water, and that it wascharged.

Water is known to have a strong absorption peak at a wavelength3.05-3.10 μm, corresponding to a symmetric OH stretch. A light source,LED31-PR, which has peak output at 3.1 μm and full width at half maximum(FWHM) of 0.55 μm, was used to irradiate water in contact with ahydrophilic surface. PERMA PURE® NAFION tubing (TT-050, 0.042 in. diam.,(PERMA PURE® is a registered trademark of PERMA PURE LLC of Cincinnati,Ohio) was suffused with a 1 μm carboxylate-microsphere suspension (2.65%solids-latex, available from Polysciences Inc. of Warrington, Pa.) witha 1:500 volume fraction, to a depth of about 1 μm. The chamber was madeusing a thin cover glass adhered to the bottom of a 1-mm thick coverslide with a 9-mm circular hole cut in the center, and was placed on thestage of a microscope (ZEISS AXIOVERT-35, with camera CFW-1310C).(ZEISS® and AXIOVERT® are registered trademarks of Carl Zeiss AG Corp.of Oberkochen, Germany.) A pinhole (available from Edmund Optics ofBarrington, N.J.), 50 μm in diameter and 0.25 mm thick, was used toobtain an incident beam of restricted diameter. A fabricated holderintegrated the pinhole and LED into a single unit with the LED mountedclose to the pinhole. The LED-pinhole axis was vertically oriented.

When the exclusion zone reached an apparent equilibrium state, theincident radiation was turned on. Optical power output was 33 μW, andthe estimated power received through the pinhole was about 2.4 nW. Afterfive minutes, the LED assembly was removed and the exclusion zone wasphotographed through the microscope. Referring to FIGS. 7A and 7B, it isapparent that even with modest IR exposure, the exclusion zone (7B) grewto approximately three times its control size (7B).

Exclusion zone width was also tracked over time. This was carried outnot only with the 3.1 μm source, but also with 2.0 μm and 1.75 μmsources (FWHM=0.16 μm and 0.18 μm, respectively). For the latter twosources, intensities were maintained at approximately 190 μW; but forthe 3.1 μm source, power was kept at the maximally attainable value, 33μW.

During the 10 min exposure at all three wavelengths, exclusion zonescontinued to expand approximately linearly (FIG. 8A). The largest effectwas seen at 3.1 μm, despite lower incident power. To determine whetherthe EZ continues to expand beyond the 10-min exposure, the 3.1 μm sourcewas left on at the same intensity as above for up to one hour. Theratios increased from 3.7±0.10 (10 min) to 4.7±0.12 (30 min) and6.1±0.17 (1 hr) respectively. Hence, the exclusion zone continued toexpand for up to at least one-hour of exposure.

Post-illumination exclusion zone size dynamics were examined. When theinfrared light was turned off after 5 minutes exposure, exclusion zonewidth remained roughly constant with fluctuations for about 30 min.Then, the size of the exclusion zone began decreasing noticeably andcontinued to decrease for approximately one hour.

To determine the effect of beam intensity on exclusion zone expansion,the 2 μm source was employed at three power levels, 0.21, 0.34, and 1.20mW. The rate of EZ expansion increased with an increase of incidentpower (FIG. 8B).

The results demonstrate that exclusion zone expansion is a function ofboth time and intensity. Exclusion zone growth depends on the cumulativeamount of incident energy.

To test whether the expansion arises out of some unanticipatedinteraction between the incident radiation and the particular type ofmicrosphere probe, microspheres of different size and composition weretested. For carboxylate microspheres of diameters 0.5 μm, 1 μm, 2 μm,and 4.5 μm at the same volume concentrations (1:500), mean expansionratios for 5-min exposure of 3.1 μm radiation were: 2.41, 2.97, 3.08,and 3.34, respectively (n=6). For varied 1 μm microspheres made ofcarboxylate, sulfate (2.65% solids-latex, available from PolysciencesInc. of Warrington, Pa.), and silica (SIO₂, available from PolysciencesInc. of Warrington, Pa.) under conditions the same as above, expansionratios were 2.97, 3.10 and 1.50. Some material-based and size-basedvariations were noted; the latter arising possibly because of differentnumbers of particles per unit volume; but, appreciable radiation-inducedexpansion was nevertheless seen under all circumstances and with allmaterials. The presence of the expansion effect is not materialspecific.

The effect of illuminating with IR at different positions relative tothe NAFION/water interface was compared. For these measurements, a sheetof NAFION 117 film (0.007 in. thick, Aldrich), approximately 6 mm longand 1.5 mm high, was held by a micro-clip (0.75×4-mm jaws, WorldPrecision Instruments) and positioned in the vertical plane near themiddle of the chamber, which was made from a rectangular glass block,length 7 cm, width 2.5 cm and height 1.5 mm with a rectangular hole,length 3.15 cm and width 1.2 cm, cut through from top to bottom and a1-mm-thick glass slide sealing from beneath. The film's upper edge waspositioned at the solution surface. The vertical scale was carefullycalibrated using a 1-mm-thick glass slide with face markings; onemillimeter corresponded to 634 divisions on the focus knob. A 50 μmpinhole was placed immediately above the specimen in order to restrictincident spot size. To estimate spot diameter at different solutiondepths, a visible source (microscope light with green filter, λ=550 nm)was substituted for the LED. Beam diameters increased approximatelylinearly from 160 μm at the solution surface, to 240 μm at 1.5 mm belowthe surface (these values are only approximate, as diameters will changewith wavelength). For periods of observation and data collection, wheresome illumination was required, intensity was minimized by use of thissame filter.

With the beam first positioned in the middle of the exclusion zone, theexpansion ratios were measured at different depths. FIG. 9A shows thatmaximum expansion occurred at a depth of approximately 450 μm from thesolution surface, and was detectable well beyond 1 mm. The fact that themaximum expansion occurred well below the surface is surprising giventhe limited IR penetration ordinarily expected in water.

With the same setup as above, the spot was then positioned at varyingdistances from the NAFION-water interface. Results are shown in FIG. 9B.Expansion was largest when light was focused in the center of theexclusion zone, and fell off on either side, although not appreciably.At deeper positions, the near-NAFION expansion peak tended to broadensomewhat, possibly because of incident-beam broadening; but, the trendwas essentially similar at all depths. The most notable finding was thateven when the beam was positioned far from the NAFION surface, theexpansion effect was appreciable.

Infrared absorption in water causes a temperature elevation. To measurelocal temperatures, an OMEGAETTE 1M datalogger thermometer HH306 wasused, with stainless-steel-sheathed, compact transition ground-junctionprobe (TJC36 series), small enough (250 μm) to fit within the exclusionzone. (OMEGAETTE® is a registered trademark of Omega Engineeering, Inc.,of Stamford, Conn.) With the incident beam positioned to elicit themaximum expansion, i.e., centered 175 μm from the NAFION surface, themeasured temperature increases are shown in Table 1.

TABLE 1 Temperature increases measured at different distances from theNAFION surface after 10 min. exposure to 3.1 μm radiation (n = 3)Distance Mean temperature increase 175 μm  1.1° C. 250 μm 0.91° C. 350μm 0.92° C. 4 mm 0.91° C. 6 mm 0.92° C.

Radiation-induced temperature increases were modest at all positions andfairly uniform over the chamber. Slight temperature variation was foundwith depth, implying that the thermal mass of the probe itself, immersedby varying extents for measurements at varying depths, did not introduceany serious artifact.

Dynamics of temperature rise were observed. The temperature increaseoccurred steadily, reaching a plateau of about 1° C. at 10-15 min aftertum-on. This plateau was attained at a time that the exclusion zonecontinued to expand (see FIG. 8A). Not only was the temperature increasemodest, but also the time course of temperature rise and exclusion zoneexpansion were not correlated.

Infrared effects were seen at depths on the millimeter scale, whereasinfrared penetration into water is anticipated to extend down only onthe micrometer scale. One possible explanation is that penetrationthrough the exclusion zone is deeper than through bulk water.

The exclusion zone expansion's spectral sensitivity was determined. Theexperimental setup was similar to that described above. The about 200 μmwide light beam emerging from the pinhole was directed to the middle ofexclusion zone, and expansion was measured 300 μm below solutionsurface. For the UV and visible sources, maintaining consistent opticalpower output at all wavelengths was achievable within +/−10% byadjusting the driver current. IR sources were considerably weaker andoutput power was maintained at a lower level, three orders of magnitudelower than in the UV-visible ranges.

For ultraviolet and visible ranges all incident wavelengths broughtappreciable expansion (FIG. 2A). The degree of expansion increased withincreasing wavelength, the exception being the data point at 270 nm,which was higher than the local minimum at 300 nm. The higher absorptionmay reflect the signature absorption peak at 270 nm characteristic ofthe exclusion zone. Clear wavelength sensitivity was also found in theinfrared region, the most profound expansion occurring at 3.1 μm (FIG.2B). Recognizing that the optical power available for use in the IRregion was 1/600 of that in the visible and UV regions, one can assumethat with comparable power, the IR curve would shift considerably upwardcontinuing the upward trend evident in FIG. 2A. The most profound effectis in the IR region, particularly at 3.1 μm.

Interestingly, the overall spectral sensitivity of expansion followsclosely the spectral sensitivity of water absorption. In both cases,there is an overall minimum in the near-UV, plus a local maximum at 2.0μm and a peak at 3.1 μm. If not by coincidence, then a connection isimplied between IR absorption and EZ expansion, although the linkage isapparently not through temperature increase, which was both modest andtemporally uncorrelated. Furthermore, increasing the bath temperatureactually diminishes exclusion zone size. Evidence that the effect isapparently non-thermal.

FIGS. 10A and 10B present evidence that negative charge buildup next toNAFION is associated with proton buildup in the bulk water beyond. FIG.10A shows the bulk-water pH transient that occurs during exclusion zonebuildup, while FIG. 10B shows the pH distribution in the bulk measuredafter the exclusion zone had formed. Whereas the exclusion zone isnegatively charged, both results, using independent techniques, confirmthat the region beyond contains an abundance of protons. Indeed,electrodes placed in the respective zones are able to deliversubstantial current to a load confirming charge separation between theexclusion zone and the bulk zone beyond.

FIG. 11 is a graph comparing potential (mV) measured as a function ofdistance from the surface of representative hydrophilic materials(NAFION and poly(acrylic acid) gel) useful in the method of theinvention; the substances are depicted as “inside” and water is“outside.” Similar negative potentials have been observed withion-exchange beads composed of crosslinked polystyrene divinylbenzenebackbones functionalized with sulfonic acid groups.

The following is a description of the methods used in the experimentsdescribe above.

Sample Preparation. NAFION surfaces, sheets or tubes, were used forcreating exclusion zones. NAFION was immersed in ultrapure water(NANOpure Diamond [trade] 1M p=18.2 MΩ-cm) to which microspheres wereadded for delineating the exclusion zone boundary. To supply incidentenergy, a series of LEDs were used. All experiments were carried out atroom temperature in a darkened room.

Light Sources and Calibration. The LEDs used for infrared illumination(available from Gist Optics Co., LTD. of ChangChun, China) came in T0-18packages with parabolic reflectors for reducing beam-divergence angle.For the visible range, the LED φ5 series (available from NICHIACorporation of Tokushima, Japan) was used. For illumination in the UVregion, LED model NSHU590 (NICHIA) emitting at 365 nm, and LED modelsUVTOP® 265 and UVTOP® 295 (available from SENSOR ELECTRONIC TECHNOLOGY,Inc. of Columbia, S.C.) encapsulated in metal-glass T0-39 packages withUV-transparent hemispherical lens optical windows, emitting,respectively, at 270 nm and 300 nm, were used. All LEDs were driven at 2kHz by a Model D-31 LED driver (available from Gist Optics Co., LTD. ofChangChun, China). Output power was regulated for consistency using amodel 1815-C optical power meter (available from NEWPORT Corporation ofIrvine, Calif.) equipped with NEWPORT model 818-UV, 818-SL and 818-IRprobes.

In another aspect, the invention provides a method for generatingelectrical energy from a volume of water through the formation of anexclusion zone at the interface of air and water. In one embodiment ofthe method, energy is applied to a volume of water contained in a vesselto provide an exclusion zone in the volume of water at the air-waterinterface and a bulk zone in the volume of water outside of theexclusion zone; a first electrode is provided in the exclusion zone anda second electrode in the bulk zone; and electrical energy is extractedfrom the volume of water by connecting a load across the electrodes.

Exclusion zones have been observed not only next to hydrophilic surfacesas described above, but also at the air-water interface of volumes ofwater contained in vessel having a surface (upper surface) exposed toair. These exclusion zones (i.e., top layer of water on the order of 1mm) appear to be solute free. In several chamber-geometrical variants,microspheres were consistently excluded from this zone and measurementsshowed that the zone had a negative potential.

It is possible that the air is not per se that was responsible for thepresence of the exclusion zone and that the exclusion zone was due tothe glass surfaces at the chamber's edge. At the glass-water interfacethe meniscus rise was commonly solute-free, implying the presence ofstructure. This structure apparently propagates along the water-airinterface, covering the water surface. In narrow chambers this cover wascommonly 1-2 mm thick, whereas in wider chambers, where the menisci aremore widely separated, the structure was thinner. However, replacing airwith nitrogen, but not oxygen, diminishes the exclusion zone implyingthat oxygen may be playing an important role.

An array of thin glass sheets, positioned parallel to one another andspaced about 1 mm apart, was constructed. The surfaces were orientedperpendicular to the air-water interface, and the top of the array layimmediately beneath the water surface. The negative electrode consistedinitially of platinum wires running along the top edge of each member ofthe glass array, situated just at the air-water interface. The positiveelectrode, placed at a selectable distance beneath the array, was aplatinum mesh.

Electrical power was extracted from these conditions, just as in thepresence of hydrophilic surfaces described above. The drop of voltage,from the initial value to the plateau, was typically only 30-35%, a moremodest drop than the situation with immersed hydrophilic surface. Thus,ambient energy could apparently better sustain the power delivery.Absolute power levels were higher. With hydrophilic surface (e.g.,NAFION) systems, 1 μA currents with 10K resistor were obtained, while inthis aspect, even with the higher resistance 200K resistor used forthese experiments, currents on the order of several μA to 10 μA wereobtainable, giving power levels in the range roughly 1 μW/cm² of surface(i.e., surface parallel to the air-water interface).

The effect of incident IR was found to be more consistent albeit lessdramatic than in the hydrophilic surface (e.g., NAFION) systems. When IRlight was applied from the onset, the drop-off of voltage was slowed byabout five or six times; and, the plateau level remained somewhathigher. When the IR was turned on sometime during the plateau, theeffect was smaller, sometimes being insignificant, other times causing aslight increase.

Several experimental variants were evaluated including the use ofdifferent types of electrode materials instead of platinum and theaddition of salts into the pure water.

Regarding electrode materials, various combinations of platinum, zinc,aluminum and copper were explored. Depending on the combination, thevoltages were either higher or lower than with platinum-platinum. In oneadvantageous embodiment, the electrode combination was platinum(negative) and zinc (positive), which gave an initial potentialdifference on the order of about 1 V.

FIGS. 10A 12-15 are graphs demonstrating the effectiveness of generatingelectrical energy from an air-water interface as described above. FIG.12 is a graph of voltage (V) over time using a platinum cathode and zincelectrode. FIG. 13 is a graph corresponding to FIG. 12 showing current(amperes) over time. FIG. 14 is a graph of voltage (V) over time using aplatinum cathode and zinc electrode using glass slides that are twice(2×) larger than those used to obtain the record shown in FIG. 12 (notevoltage increase). FIG. 15 is a graph corresponding to FIG. 14 showingcurrent (amperes) over time. When using electrodes of two differentmetals, rather than the same metals for each electrode, some differenceof output power may be due to the metals' electrochemical surfacepotentials.

Regarding the addition of salt, modest amounts of salt caused thepotential difference to increase. To check the effect, the salt wasadded in low concentration during the voltage falloff. Voltage magnitudeimmediately increased, followed by a less steep falloff than in theabsence of salt, by 0.2 to 0.3V.

While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the invention.

What is claimed:
 1. An electrical apparatus, comprising: a containerincluding a hydrophilic surface, the container being configured to holdwater adjacent to the hydrophilic surface; a first electrode disposedadjacent to the hydrophilic surface and configured to be at leastpartially submerged within water in the container; a second electrodedisposed away from the hydrophilic surface and configured to be at leastpartially submerged within the water container; and an electricalcircuit operatively coupled between the first and second electrodes;wherein the container is configured to receive energy such that thewater spontaneously forms a negatively charged region adjacent to thehydrophilic surface and around the first electrode to continuouslygenerate electrical energy.
 2. The electrical apparatus of claim 1,wherein the negatively charged region in the water adjacent to thehydrophilic surface comprises an exclusion zone.
 3. The electricalapparatus of claim 1, wherein the negatively charged region in the watercauses an electrical potential to form between the first and secondelectrodes, and the first and second electrodes provide electricalcurrent to the electrical circuit.
 4. The electrical apparatus of claim1, wherein the electrical circuit includes a load configured todissipate electrical current driven by a differential charge between thewater around the first electrode and water around the second electrode.5. The electrical apparatus of claim 1, wherein the first electrode isless than 1 mm away from the hydrophilic surface.
 6. The electricalapparatus of claim 5, wherein the first electrode is less than 700 umaway from the hydrophilic surface.
 7. The electrical apparatus claim 6,wherein the first electrode is less than 200 um away from thehydrophilic surface.
 8. The electrical apparatus of claim 1, wherein thesecond electrode is more than 200 um away from the hydrophilic surface.9. The electrical apparatus of claim 8, wherein the second electrode ismore than 700 um away from the hydrophilic surface.
 10. The electricalapparatus of claim 9, wherein the second electrode is more than 1 mmaway from the hydrophilic surface.
 11. The electrical apparatus of claim1, wherein the container is configured to allow exposure of the water toelectromagnetic radiation.
 12. The electrical apparatus of claim 11,wherein the electromagnetic radiation comprises infrared radiation. 13.The electrical apparatus of claim 1, wherein the container is configuredto allow exposure of the water to electromagnetic radiation of greaterthan 200 nanometers wavelength to cause enhanced formation of thenegatively charged region.
 14. The electrical apparatus of claim 1,wherein the container is configured to allow exposure of the water toelectromagnetic radiation of less than 10,000 nanometers wavelength tocause enhanced formation of the negatively charged region.
 15. Theelectrical apparatus of claim 1, wherein the container is configured toallow exposure of the water to electromagnetic radiation of about 3000nanometers wavelength.
 16. The electrical apparatus of claim 1, whereinthe water and hydrophilic surface are arranged to receiveelectromagnetic radiation that causes the negatively charged region toform more quickly compared to the spontaneous formation of thenegatively charged region absent the electromagnetic radiation.
 17. Theelectrical apparatus of claim 1, wherein the water and hydrophilicsurface are arranged to receive electromagnetic radiation that causesthe negatively charged region to extend farther from the hydrophilicsurface compared to the extent of the negatively charged region absentthe electromagnetic radiation.
 18. A method for providing electricalcurrent to a circuit, comprising: applying energy to water disposedadjacent to a hydrophilic surface such that the water spontaneouslyforms a negatively charged region that extends away from the hydrophilicsurface; supporting a first electrode in the water adjacent to thehydrophilic surface within the negatively charged region; supporting asecond electrode in the water away from the hydrophilic surface outsideof the negatively charged region; and outputting electrical current fromthe first and second electrodes to a circuit operatively coupled betweenthe first electrode and the second electrode.
 19. The method forproviding electrical current to a circuit of claim 18, wherein applyingenergy to water disposed adjacent to a hydrophilic surface tospontaneously form a negatively charged region that extends away fromthe hydrophilic surface further comprises causing a non-zero electricalpotential to form between the first and second electrodes.
 20. Themethod for providing electrical current to a circuit of claim 18,wherein applying energy comprises applying electromagnetic radiation.21. The method for providing electrical current to a circuit of claim18, wherein applying energy comprises applying infrared radiation. 22.The method for providing electrical current to a circuit of claim 18,wherein applying energy comprises exposing the hydrophilic surface andthe water to electromagnetic radiation that causes the spontaneousformation of the negatively charged region to occur faster than thespontaneous formation of the negatively charged region absent theelectromagnetic radiation.
 23. The method for providing electricalcurrent to a circuit of claim 18, wherein applying energy comprisesexposing the hydrophilic surface and the water to electromagneticradiation to cause the negatively charged region to extend farther awayfrom the hydrophilic surface than the extent of the negatively chargedregion absent the electromagnetic radiation.
 24. The method forproviding electrical current to a circuit of claim 18, wherein applyingenergy comprises exposing the hydrophilic surface and the water toelectromagnetic radiation to cause the negatively charged region toextend away from the hydrophilic surface for a longer period of timethan the extent of the negatively charged region absent theelectromagnetic radiation.
 25. The method for providing electricalcurrent to a circuit of claim 18, wherein applying energy comprisesexposing the hydrophilic surface and water to electromagnetic radiationto cause a greater amount of electrical current to be output relative tothe amount of electrical current output absent the electromagneticradiation.
 26. The method for providing electrical current to a circuitof claim 18, wherein applying energy comprises applying electromagneticradiation; and wherein the spontaneous formation of the negativelycharged region that extends away from the hydrophilic surface and acollection of electrical current by the first and second electrodestransforms the electromagnetic radiation energy to electrical energy.